Background and objectives: Freezing is a practical approach for cell preservation for retrospective studies. The aim of this work was to check the cryopreservation impact on B cell chronic lymphocytic leukaemia phenotype.
Material and methods: Blood samples from 15 CLL patients were analyzed freshly and after freezing at -196 degrees C, without separation, and thawing. Results were compared by Student's paired t-test.
Results: The phenotype of fresh CLL cells was as follows: CD19+, CD5+, faint CD20, CD23+/-, weak CD22 and sIg, CD37+, HLA-DR+, FMC7-. After cryopreservation, the percentage of CD5 and CD23 positive cells decreased, whereas HLA-DR positive cells increased moderately. The CLL Matutes's score was modified in 6 cases out of 15 (40%).
Conclusion: Cryopreservation modifies B cell chronic lymphocytic leukaemia phenotype, by decreasing CD5 and CD23 expression.